Electro-mechanical systems are commonly used to store and retrieve articles. One well-known example of such a system is a kiosk. Kiosks generally serve the purpose of selling articles such as snacks, beverages, and newspapers. Article selection is commonly performed by selecting an item using a user interface. For example, a user interface may include push buttons that enable a user to choose a desired article. Kiosks also commonly include a system for receiving payment for a selected article. Once an article is selected and the required payment has been received, the desired article is delivered to a dispensing area where the user may retrieve the article.